Esacus is a genus of bird in the stone-curlew family Burhinidae. The genus contains two species: the great stone-curlew and the beach stone-curlew.
The name is from Ancient Greek aisakos an unidentified bird variously associated with a robin, a shorebird or a cormorant.

1/ Great stone-curlew or great thick-knee (Rẽ mỏ to, Esacus recurvirostris)
The specific epithet recurvirostris combines Latin recurvis meaning "bent backwards" with -rostris meaning "-billed".